The immunomodulatory protein thymopoietin has been isolated from bovine and human thymus. Additionally, small peptides have been chemically synthesized which mimic the biological activity of thymopoietin. See, e.g. U.S. Pat. No. 4,505,853 and corresponding EP application No. 146,266.
A large body of articles and patents have now been published relating to such proteins and synthesized peptides. U.S. Pat. No. 4,190,646 discloses the pentapeptide thymopentin which is the active site of thymopoietin and has the sequence Arg-Lys-Asp-Val-Tyr SEQ ID NO: 1 , as well as peptide compositions in which various groups are substituted onto the amino and/or carboxyl termini of this pentapeptide.
Thymopoietin is known to regulate cholinergic neuromuscular transmission [G. Goldstein and W. W. Hoffman, J. Neurol. Neurosurg. Psychiatry, 31:453-459 (1968); and G. Goldstein, Nature, 247:11-14 (1974)]. Thymopoietin is present within the brain, as are thymopoietin receptors (TPR), so that thymopoietin is almost certainly involved in brain function.
More recently, thymopentin has been identified as an antagonist of stress-induced changes, exhibiting stress-protective activity [V. Klusa et al, Regulatory Peptides, 27:355-365 (1990)].
There remains a need in the art for additional peptides useful as diagnostic agents and/or therapeutic agents useful in treating dysfunctions of the immune system in humans and other mammals, including those associated with aging and various physical conditions, as well as peptides useful for treating disorders in central nervous system functions.